The present invention relates generally to power operated garage doors and specifically to a garage door opening mechanism for use with a door which is concealed in the exterior wall of a building.
It has become very common for houses to be constructed with one or more automobile garages built into the house. With the garage being integrated with the home rather than in a separate building, the residents of the home have the convenience of being able to enter and exit their automobiles without being exposed to the weather and at a minimum distance from their living areas in the home. The garage doors of such built-in garages are normally opened and closed by power operated apparatus which may be controlled by means located within the house or by remote control means located within the automobile. This arrangement allows the residents to enter and exit their automobiles within the safety and shelter of their home without being exposed to the weather or other risks.
The typical power operated garage door comprises a series of horizontally extending panels which are hingeably connected to each other and are supported for movement from a vertical position closing the garage opening to a horizontal position along the ceiling of the garage. Rollers which support the panels are received in channel-shaped tracks which extend vertically on either side of the door opening and then extend horizontally along the ceiling of the garage.
There are also one-piece doors which are supported by various types of mechanisms to move from the vertical closing position to a generally horizontal and elevated open position. The most common type of one-piece door is supported at the midpoint of its sides by swivel hardware that rotates the door between its vertical and its raised horizontal position. During this movement the bottom of the door typically moves outwardly so that the door projects partially outside of the door opening. This type of one-piece door presents several disadvantages in being difficult to seal when closed and in requiring a clearance space in front of the door to permit opening movement. Another type of one-piece door which does not project outwardly of the door opening is shown in the stet to Kees U.S. Pat. No. 1,252,448 which supports the lower edge of the door in a set of generally vertical tracks and supports the upper edge of the door in a set of generally horizontally extending tracks. A similar one-piece door support is disclosed in Pemberton, et al. U.S. Pat. No. 3,568,365.
It is typical of most prior art garage doors (other than the swivel mounted doors discussed above) to dispose the doors completely within the building, inside of the building wall, so that the door may move upwardly to its open position. If the door projected into the door opening, it would prevent the door from moving vertically without first being withdrawn inwardly. As a consequence, garage doors are typically recessed or inset from the face of this wall defining the opening by a distance of eight to twelve inches. Many attempts have been made to provide ornamentation or decoration on the doors to enhance their appearance. However, the recessed position of the doors makes it difficult to create an attractive appearance which blends with the architectural appeal of the house.
In recent years the increase in land cost has caused larger homes to be constructed on smaller pieces of property. The smaller lot size often necessitates that the garage be placed on the front side of the home where the garage door further detracts from the appearance of the house. The trend toward the inclusion of two and three car garages further magnifies the problem of providing an attractive and appealing home design with two or three garage door openings located in the wall of the building.
In addition, to the different types of garage doors that have been developed and are in current use, there are power drive mechanisms that have been developed for use with these various types of doors. The most common type is used with the multiple panel door and simply connects directly to the upper panel and moves horizontally back and forth on the ceiling to raise and lower the door. A screw or chain mechanism is used to drive the door. Such doors normally include springs to counterbalance the weight of the door so that the door may be operated manually. Therefore, the power mechanism drives the door downwardly or closed as well as driving it in the raising or opening direction.
Because of the substantial power required to move the garage door, there are safety considerations involved in the design of controls for power operated garage doors. Of greatest concern is the possibility of the door being closed when someone or something is in the path. With the power needed to move the substantial mass of the garage door, the door has the capacity to cause serious injury if it impacted a person as it moves toward the closed position. As a consequence, standards have been established requiring that power operated garage doors be equipped with safety devices to prevent injury to a person in the path of the doors as they close.
These safety devices include light beam operated switches to sense obstructions in the door opening, pressure operated switches on the edge of the door, and control circuits responsive to the speed or load on the door driving motor. The latter type of circuits are preferred since they are the least expensive, involving the addition of relatively inexpensive components to the drive motor control circuit. These circuits sense the engagement of the door against an obstacle by the drop in rotational speed of the drive motor or the increase in motor current as the motor begins to stall on encountering an obstacle. There are also garage door drive means including mechanical load sensing means between the motor and the door drive to mechanically sense the load increase and provide a signal to reverse the motor direction of rotation. Upon sensing such an obstacle to closing movement of the door, the control circuit causes the motor to stop or reverse, thereby preventing injury if the obstacle is a person. Safety devices including such motor control circuits responsive to motor speed or load are common and well known in the power operated garage door opening field.
There are limitations on the types of power operated doors to which the motor control safety circuits are applicable. Thus, there is a type of door drive mechanism that uses the motor to raise the door and allows the door to close under the force of gravity. This approach is typical of industrial or commercial power operated doors. Another type of door drive mechanism utilizes a roller chain or screw to drive the door in both the opening or closing direction. The chain or screw drive is most commonly used with the hinged panel garage doors described above. Since the chain or screw drive mechanism powers the door in the closing direction, it is easily adapted to use a safety circuit responsive to motor load or speed to prevent injury to an obstacle encountered as the door moves in the closing direction. On the other hand, the industrial/commercial drive mechanism using a cable to raise the door and lower or close it by gravity is not adaptable to the use of the above described motor safety circuit. Accordingly, it has been necessary to utilize pressure sensitive switches and light beam controlled switches to provide the safety protection required in connection with the industrial type doors which are raised by a motor driven cable and lowered by gravity.